• Please review our updated Terms and Rules here

Burroughs B6700 Memory...

The CPU & memory cabinets alone took one entire wall of a fairly large room, and it had the most impressive panel of blinkenlights I've ever seen; it was in house for a couple of months being tested and set up for the Metro Toronto police department, and when idle it displayed the MTP crest on its panel of lights which ISTR was about 3 feet square; those bulbs alone probably would have heated one or two small rooms...
Yeah, that was the big thing for the software guys to recompile the MCP and put the company logo in the idle loop. Mine said "AC" most of the time. I remember one time they were upgrading the MCP and wanted it to be obvious they were on the new vesion. So they put the logo in "negative video". I was not happy ;-) being the one who had to change the bulbs.
That was a large 6700, we had three CPUs 2 IOs and 4 DCPS, at max. After they got the 7700 the 6700 became the development system, and we reduced it down to a single CPU.
 
The B6700 hardware manual lists several other voltages too: for the core-memory system there are +1V, -50V, +63V and +37V. In another part of the CPU/DCP system there are also +12V and -12V - the power supplies must have been quite complex to supply so many different voltages.

Burroughs appear to have their own logic integrated circuits listed as CTuL (Complimentary Transistor Micro Logic), they were positive logic, "true" was +2.5V and "false" was -0.5V


Jim: do you happen to remember what was special about the B6748 "restricted model"? it is not listed in the reference manual I have but I found another reference to it in Doran's book.

Sorry, I never heard of the B6748.

Those power supplies were distributed around the system. The AC module converted the input power to DC and routed it to each cabinet where the switching supplies there generated the needed voltages for each cabinet. The 4.75,-2 was one supply, +-12 another. Some of the newer cabinets were independently powered like the DCP and maybe even this particular memory subsystem.


I believe this was the demo system at Burroughs WHQ in Detroit
 
Last edited:
2012 or bust!

I'm running out of excuses, but for 2012 I want to get the Cromemco System 3 (Cromix), LDP-88 (UCSD p-System), and PDP-8/E (EduSystem) functional.

I noticed on my System 3 that some of the large power supply caps have leakage, need to be replaced. It's on my 2012 list too...good luck to you.
 
Jim - can I use this picture on my website please? it is particularly interesting as it shows a dual CPU configuration.

It's OK by me, but I guess it belongs to Unisys... It was from some sort of sales package I believe. Since it was essentially advertising, I don't think they'd mind. ;-)

It has dual maintenance displays... I never really noticed that before. That wasn't necessary for a dual CPU configuration. The panel could be switched to any CPU or I/O processor.
 
Last edited:
It has dual maintenance displays... I never really noticed that before. That wasn't necessary for a dual CPU configuration. The panel could be switched to any CPU or I/O processor.
But was it possible to have both displays connected to the same CPU? I guessed it was dual CPU since both are displaying the idle MCP "B"urroughs light-pattern so I assumed two different CPUs.
 
But was it possible to have both displays connected to the same CPU? I guessed it was dual CPU since both are displaying the idle MCP "B"urroughs light-pattern so I assumed two different CPUs.
Definitely bigger than the one we had...

Are those TD800s? I sold mine long ago, but still have a keyboard somewhere; should use that for something.

Nige, did you ever hear any more from the fellow in CA with the TD700? Wonder what happened to it.

Sorry for hijacking the thread BTW, but BBM comes up so rarely...
 
But was it possible to have both displays connected to the same CPU? I guessed it was dual CPU since both are displaying the idle MCP "B"urroughs light-pattern so I assumed two different CPUs.

It's been such a long time... but I'd guess both panels could be on the same CPU. Anyway, for a demo system, it might be possible for all the CPUs to be in the idle loop. No telling what the configuration of that system was.
 
Definitely bigger than the one we had...

Are those TD800s? I sold mine long ago, but still have a keyboard somewhere; should use that for something.

Yeah, those are TD800 displays. The 830 was about half that deep. Interesting thing about those... the monitor part of the terminal was an OEM assembly. It was connected to the logic cage via a BNC connector inside. I really messed with the sales guy by taking that off on my scrapped unit and connecting it to a VCR. ;-) I used it for a couple years on my homebrew Z80 along with the keyboard.. then it moved to the Atari 800 until I could afford a color monitor.
 
It's great to see a couple of pictures creating this discussion.
In the mean time I have received a few more boards of the B6700, which I will post in the next couple of days.

But also a boards of a Cromemco machine (1 memory and 2 IO). Also pictures of these will be posted.

I will see if I can put the big boards on a scanner to get more details on chips etc.
 
More photo's

More photo's

IMAG0058.jpgIMAG0059.jpgIMAG0060.jpgIMAG0061.jpgIMAG0064.jpg

A bit quicker then expected.
3 x Burroughs 6700 - No idea what the cards are.
2 x Cromemco (1 x memory, 1 x IO).

Raoul.
 
While we're posting Burroughs pictures, here's the operator console from a B2700; not quite the same as the 6700 ;-)

I even have a picture of myself operating this 2700 in my Burroughs days somewhere; will have to dig for that one of these days...

(As it happens I also have piles of Cromemco boards, systems & manuals from my days as a Cromemco sub-dealer...)

B27con1.jpg

Edit: Wow, that's an old picture; I haven't smoked in years ;-)
 
mainframe nostalgia

mainframe nostalgia

I think that first B6700 card is part of the memory buss interface. That small white tag near the 20 pin edge connector lists the card slot where it belongs. My memory may be fooling me, but I think the first letter being "B" means it went in the "multiplexor", otherwise known as the I/O processor.
 
It has dual maintenance displays... I never really noticed that before. That wasn't necessary for a dual CPU configuration. The panel could be switched to any CPU or I/O processor.

Reviving this very old thread, I found out from my friend PK, that this was the "failsoft" model of the B6700 that was introduced around November 1972, this was the idea of duplicate-everything so it would keep running no matter what.

Details here:
http://www.retrocomputingtasmania.c...inframe/gallery#TOC-Burroughs-FailSoft-models
 
Duplicate parts can bite you though... I had a 6700 that had a multiplexor problem... So the plan was to reconfigure to make the B mpx the master and take the failed A mpx ofline for repair. But we didn't realize the B mpx had it's own problem... the time-of-day register had a stuck bit down near the bottom and was running about 4 times faster than normal. Normally, the system uses the A mpx's TOD... By making B the A mpx the system time ran up into the next day before anyone realized it. They had to shut down and let the real world catch up with the computer. ;-) Funny now, 35 years later, but embarassing then...
 
What a great story! do you have any photographs from that era you can share?

I'm afraid not. My particular customer was a bit paranoid about cameras on site. Probably no more than any other company, but the one time I came to work with my camera, I had to go back and leave it in the car.
 
Back
Top